It's 68 440 I built it in the 80s, used trw pistons,l and used a ring filer and checked the gap inside a fresh bored 030 block. But the did sit a couple years at a time. I used to run it at the track. Damn good motor ran 12s in a challenger. Was just going to swap it to another car thought I'd take peek inside.Ring gap was dead nuts on when I put it together.chrome moly